Question

1. How many ATOMS of carbon are present in 2.43 moles of carbon tetrabromide? atoms of carbon 2. How many MOLES of bromine are present in 1.72x1022 molecules of carbon tetrabromide? moles of bromine.

Answer 1

1)

1st find number of CBr4 molecules

use:

number of molecules = number of mol * Avogadro’s number

number of molecules = 2.43 * 6.022*10^23 molecules

number of molecules = 1.463*10^24 molecules

1 molecule of CBr4 has 1 atoms of C

So,

number of C = number of CBr4

= 1.463*10^24 atoms

Answer: 1.46*10^24 atoms

2)

1st find mol of CBr4

use:

number of mol = number of molecules / Avogadro’s number

number of mol = 1.72*10^22 / 6.022*10^23 mol

number of mol = 2.856*10^-2 mol

1 mol of CBr4 has 4 moles of Br

So,

number of moles of Br = 4*number of moles of CBr4

= 4*2.856*10^-2 mol

= 0.114 mol

Answer: 0.114 mol